i got a 91 integra with a built (mild) ls/vtec. I've never had problems with a water temp until now. I'm losing coolant from a small crack (or its just overflowing) in the reservoir tank. I keep having to fill the radiator (just bought new) before i drive it and it stills heats up! I replaced the temp. sensor, althought its used, but thats about all i've done. I just ordered a new coolant tank and new temp. switch and thermostat from spoon that i havent put in yet. What could be the problem??

p.s. i've had this motor for about a year and its never had this problem till now

 

Find someone with a pressure tester and pump up the system, make sure you pinch off the hose going to the reserve tank. This will rule out everything other than the reserve tank.